Which of the Following Is TRUE Regarding Biological Influences on Homosexuality

Which of the following is TRUE regarding biological influences on homosexuality?

A) Researchers considered hormones to be a factor in the past,but more recent research has determined that parenting style is the most influential in determining if someone is homosexual.
B) Theories suggesting biological influences on sexual orientation have been disproven.
C) Genetics appear to be involved in determining sexual orientation.
D) Scientists have isolated a specific gene which seems to be the primary factor in determining sexual orientation.